1. Technical Field
The present invention relates to a gathering line and is particularly directed to a reject control system for use along a gathering line.
2. Background Art
A gathering line includes a plurality of hoppers and a gatherer chain defining a plurality of chainspaces. Each chainspace corresponds to one collating space along the gathering line. Each collating space moves downstream and passes the hoppers in turn to receive a signature from each of the hoppers to form a collated assembly of signatures in the collating space. A feeding mechanism is associated with each hopper for feeding a signature from the hopper to a collating space. The feeding mechanism associated with each hopper is operated so that a signature is transferred at the proper time from the hopper to a collating space.
A reject control system is associated with the gathering line. The reject control system typically includes a shift register having a plurality of adjacent bits as is known. At any given moment, each bit contains information indicative of the condition of one collating space along the gatherer chain. The particular collating space with which the information contained in a particular bit is associated depends upon the position of the collating spaces relative to the hoppers. The information contained in the particular bit is shifted to a "downstream" bit as is known when the collating spaces move downstream relative to the hoppers. A controller scans the information contained in each of the plurality of bits to control operation of the gathering line.
If a misfeed condition occurs at a particular hopper and a particular collating space, the bit associated with the particular collating space at that moment is set. When the controller scans the bits of the shift register and detects that the bit associated with the particular collating space is set, the feeding mechanisms of all hoppers located downstream from the particular hopper at which the misfeed condition occurred will not later feed any signatures to the particular collating space. A reject mechanism located at the end of the gathering line may be used to reject the collated assembly of signatures in the particular collating space at which the misfeed condition occurred.
A disadvantage of using a shift register in which each bit contains information indicative of the condition of one collating space at a given moment is that, when a misfeed condition occurs at a particular hopper and a particular collating space, the setting of the associated bit at that moment must be exactly timed. The setting of the associated bit must be exactly timed so that the correct bit is set and not a bit located adjacent the correct bit. The setting of the correct bit in the event of a misfeed condition at a particular hopper and a particular collating space is made even more difficult when timing of the feeding mechanism associated with the particular hopper is routinely changed.